Hi LL,
Thank you for posting your question in the Microsoft Q&A Forum. I understand that your emails before 15/09/2025 have disappeared. I’m really sorry for the inconvenience.
Please check Outlook on the Web (OWA) at https://outlook.live.com. Log in and browse to see if your missing emails are still there. On the web, also go to Settings > Mail > Rules and Settings > Mail > Forwarding to remove any suspicious rules or forwarding setups.
Additionally, on Classic Outlook for Windows (Cached Exchange Mode):
- Go to File > Account Settings > Account Name & Sync Settings
- Set “Mail to keep offline” to All (or multiple years)
- Restart Outlook
You may also consider turning off Cached Exchange Mode for future use.
If you need to contact Microsoft Support, please follow this step:
- Go to Contact Support.
- Type “lost account” > Scroll down and click Contact Support (please skip all troubleshooting steps or similar articles if you just want to contact Microsoft Support).
- Sign in > Select Products and Services > Microsoft 365 and Office > Outlook > Chat with a support agent in your web browser.
If your problem persists or you need any assistance, feel free to ask me by clicking "Add Comment". Thanks for your effort.
If the answer is helpful, please click "Accept Answer" and kindly upvote it. If you have extra questions about this answer, please click "Comment".
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Best regards.